Electrometallurgical process for extracting copper from its ores.



UNITED STATES PATENT OFFICE.

LUCIEN JUMAU, OF PARIS, FRANCE.

ELECTROMET ALLURGICAL PROCESS FOR EXTRACTING- COPPER FROM ITS ORES. fl

Specification of Letters Patent.

' Patented April 7, 1908.

' Application filed January 19, 1907. Serial No. 353,062.

To all whom itmay concern:

, Be itaknown that I, LUCIEN JUMAU, citizen of France, residing at Paris, in the said Republic, have invented new and useful Im- 5 provements 'in Electrometallurgical Processes for Extracting-Copper from Its Ores, (for which a French patent of addition, N 0. 6,477., of July 11 1906,.has been obtained) of which the following is a specification.

My invention relates to an improved electrolytic process for obtaining pure metallic copper fronipits ores, and it consists in the steps and claimed.

My invention is especial] adapted for the fluoargses herein described and economical treatment of so fid ores "n which the sulfur dioxid produced in roas ing said ores is'utilized in subsequent steps of the process.

fid ores, the ores are subjected to a preliminary roasting to convert the copper salt into an oxid; the complete conversion of the co per into an oxid 'is not necessary, since t e presence of a portion of coppersulfate is permissible in the operationof my invention.

The roasted ore is lixiviated by an ammoniacal solution, such as a sulfate or a sulfite of ammonium or a mixture of the two. The lixiviation is preferably performed at a raised temperature, and the copper is freely dissolved in the ammoniacal solution; 70'grams of copper bein readily dissolved per liter of the solution. he solution is then subjected to the action of sulfur dioxid; this Ste being preferably performed by passing through the solution the sulfur dioxid produced during the preliminary roasting of the sulfid ores. It is preferable to drive off the free ammonia from the solution previous to treating itwith thesulfur dioxid, and to employ such ammonia in the lixiviation of a subsequent quantity of ore.

The treatment of the ammoniacal solution with sulfur dioxid is preferably performed at a raised temperature, and the reaction may be expressed as follows:

A precipitate of copper containing cuprous sulfite, such as a cuproso-cupric suliite is thrown down and the remaining solution may be employed for lixivia-ting a subsequent quantity of ores by driving off the sulfur dioxid dissolved in the solution and In the application of my invention to sulmonia sufficient to neutralize t e solution.

The extra supply of ammonia can be obtained by treating with lime the ammonium sulfate with which the lixiviating solution becomes enriched the action may be expressed as follows: Ca0+(NHQ,S0,=CaSO,+2NH +H,O.

' The cuproso-cupric sulfite, which is only slightly'soluble in water, is dissolved in an ammoniacal solution, such as the sulfate or sulfite of ammonium.

When the cu 'roso-cu ric sulfite is dissolvedas above escribe in an ammomacal solution, a resultant solution is produced containing cuprous sulfite mixed with ammonium sulfite.

In previous processes for the electrolytic deposition of metallic copper from an ammoniacal cu rous solution, it has been necessary to empF tro ysis, since the deposited. copper is found to be dissolved in the ammomacal cuprous solution, thereby rendering the process commercially expensive and wasteful; the action beingexpressed as follows:

- Thus on rous'hydrate is dissolved in the ammoniaca solution during the electrolytic process, and acts as a depolarizing agent; the action may be stated as follows:

This double transformation results in an undesirable loss of electric energy in the electrolytic deposition of copper from the solu-,

tion without the employment of a diaphragm. I havefound that this practical defect can be efliciently eliminated by passing carbonic acid gas through the solution to saturate the latter duringthe electrolysis. This step converts the ammonia of the solution into the form of a carbonate, from which the copper is readily deposited in a very satisfactory manner; the passage of the carbonic acid gas also acting mechanically to maintain a circulation of the electrolyte.

The above described employment of caroy a diaphragm during the elecprocess, but the'purpose thereof could be accomplished by employing carbonate of ammonia as the ammoniacal solution pre- 7 viously described for dissolving the cuprosocupric sulfite. The solution is then subjected-to'electrolytic action for precipitating the copper in a ure metallic form.

I have descri ed a preferred and satis- 10 factor process, but, obviously, changes could he made within the spirit and scope of my invention.

Having thus described m invention, what I claim as new therein an desire to secure by Letters Patent is: I l

1. The herein described electrolytic process for obtainingpure copper from its ores, which consists in llxiviating the ores with an ammoniacal solution, precipitating the copper from said solution in the form of a precipitate containing cuprous sulfite, dissolving saldcuprous sulfite in an ammoniacal solu tion, and in subjecting said last solution to electrolytic action in the presence of car- 5 bonate of ammonia. v I

2. The herein described electrolytic process for obtaining ure copper from its ores, which consists in xiviating the ores with an ammoniacal solution, preci itating the copper from said solution in t e form of a precipitate containing cuprous sulfite, dissolving said cuprous sulfite in an ammoniacal solution, transforming said ammoniacal solution to acarbonate, and subjecting said solution to electrol tic action.

3. The erein described electrolytic process for obtaining pure copper from its ores, which consists in hxiviating the ores with an ammoniacal solution, precipitating the copper from said solution in the form of a precipitate containing cuprous sulfite, dissolving said on roussulfite in an ammoniacal solution, su jecting said solution to electrolytic action, and simultaneously assing a current of carbonic acid gas throng said solution. In testimony whereof I have signed my name to this specification in the presence of two subscribing Witnesses.

' LUCIEN JUMAU. Witnesses: JULEs FAYOLTET, EUGENE PIGHON. 

